Using Web of Science data, portfolio analysis in terms of journal coverage can be projected onto a base map for units of analysis
such as countries, cities, universities, and firms. The units of analysis under study can be compared statistically across
the 10,000+ journals. The interdisciplinarity of the portfolios is measured using Rao-Stirling diversity or Zhang et al.'s
improved measure 2D3. At the country level we find regional differentiation (e.g., Latin American or Asian countries), but
also a major divide between advanced and less-developed countries. Israel and Israeli cities outperform other nations and
cities in terms of diversity. Universities appear to be specifically related to firms when a number of these units are exploratively
compared. The instrument is relatively simple and straightforward, and one can generalize the application to any document
set retrieved from the Web of Science (WoS). Further instruction is provided online at http://www.leydesdorff.net/portfolio.

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